The present invention relates to a low-cost self-contained disposable emergency breathing system for individual use and particularly relates to a compact system readily deployable for filtering ambient toxic air and exhausting exhaled air into and from a hood whereby breathable air for life support is provided over a predetermined length of time.
Self-contained emergency breathing systems have been proposed and constructed in the past. One such system is disclosed in U.S. Pat. No. 5,315,987, of common assignee herewith. In that system, a canister containing a filter includes a mouthpiece and a hood deployable upon opening the canister to envelop an individual""s head. Nose clips are provided whereby when the individual grips the mouthpiece, ambient air flows into the filter and passes into the mouthpiece, supplying filtered breathable air to the individual. Upon exhalation, air passes through the mouthpiece into the hood, which loosely confines the individual""s head. The exhaled air passes from the hood to atmosphere. While such system has proven eminently satisfactory in the past, it is desirable to provide a system having a mask in the form of an oral nasal cover. Many believe that an oral nasal cover has a negative pressure which induces inward leakage of the smoke or toxic gases, notwithstanding the conventional practice of employing a strap to secure the mask about the individual""s face. It is therefore desirable to provide a mask which does not require a strap and which can be secured to the individual""s face solely by biting down on a mouthpiece whereby the oral nasal mask can be readily, easily and quickly applied to the individual""s face.
In accordance with a preferred embodiment of the present invention, there is provided a personal emergency breathing system including an oral-nasal mask having a generally frustoconically-shaped body formed of an elastic non-porous material such as neoprene overlaid by a protective shell formed of a plastic material. The body has on a first surface oral and nasal cavities for overlying an individual""s mouth and nose, respectively, and a peripheral seal for sealing about the individual""s nose and mouth. The body also includes a chamber opening through a second surface at the forward end of the body opposite the first surface for receiving a filter. Preferably, the chamber is cylindrical and the filter is frictionally retained in the chamber. Overlying the forward end of the body is a protective, preferably luminescent disk or cap spaced from the chamber opening enabling ambient air to flow between the cap and the body into an air inlet of the filter. Air is thus transmitted through the filter into a mouthpiece carried by and projecting from the first body surface.
The mouthpiece projects from the first body surface and terminates in a bite block having a bulbous, outwardly converging surface for gripping by the individual""s teeth. The pressure of the individual""s teeth on the converging surface biases the mask for movement toward the individual""s face, maintaining the peripheral seal about the body in sealing engagement about the individual""s nose and mouth. The mouthpiece carries an inhalation check valve enabling inhalation of filtered air and excluding backflow of exhaled air into the filter. The mouthpiece also includes exhalation check valves enabling flow of exhaled air into the hood about the individual""s head and preventing backflow of air from the hood into the mouthpiece.
In an alternate embodiment hereof, the chamber in the body has an opening through the first surface sized to receive the air filter. In this form, the air filter, mouthpiece, check valves and exhaust passages form a sub-assembly receivable in the chamber through the opening in the first surface. The body includes a pair of slots opening into the chamber and through the first surface for receiving exhalation ducts. As in the previous embodiment, the individual breathes filtered air passing through an air inlet at the forward end of the body, through the air filter, past the inhalation check valve and into the mouthpiece. Exhaled air passes into the mouthpiece and into the exhalation ducts for egress into the hood about the individual""s head.
A substantially rigid shell is disposed about the conically-shaped surface of the body in both of the foregoing embodiments. The hood is preferably secured between the shell and outer margin of the body adjacent the seal. The hood has an opening, preferably with a drawstring, such that the hood can be disposed over the individual""s head and drawn tightly, but not in sealing relation, about the individual""s neck. A suitable hood for this purpose is described and illustrated in U.S. Pat. No. 5,113,527.
The air filter preferably is provided in stages having a particulate filter, a carbon filter and a monolithic filter formed of a ceramic substrate for converting carbon monoxide to carbon dioxide. Also, a Hepa filter can be used if desired. It will be appreciated that the system is constructed about the elastic non-porous body which not only ensures a seal about the individual""s face but also anchors the mouthpiece, hood and shell and provides a chamber in which the filter can be inserted and replaced as needed. The elastic body also serves as a shock-absorbing mass about the filter, provides a nasal cavity, as well as nose pads, to close the individual""s nose and, in one embodiment, forms ducts enabling escape of exhaled air from the mouthpiece into the hood and through the neck opening of the hood into the atmosphere.
It will be appreciated that with the foregoing construction a combined oral/nasal cup and mouthpiece with the attendant advantages of each are provided. The oral/nasal cup provides a comfortable fit without the need for a nose clip and the need to apply such clip about the individual""s nose. The mouthpiece greatly improves the seal between the filtered air and exhaled air/smoke or toxic gas.
In a preferred embodiment according to the present invention, there is provided a personal emergency breathing system comprising a shaped body formed of an elastic non-porous material having along a first surface thereof a perimetrical seal for sealing about an individual""s nose and mouth, a mouthpiece carried by the body and projecting from the first surface thereof terminating in a bite block for gripping by the individual""s teeth, the bite block being shaped to draw the body toward the individual""s face to maintain the seal about the individual""s nose and mouth upon the individual biting down on the bite block, the body having a chamber with an opening through one of the first surface and a second surface opposite the one surface and in communication with the mouthpiece, an air filter disposed in the chamber for filtering ambient air and having an air inlet for receiving ambient air and an air outlet for passing filtered air into the mouthpiece, a substantially rigid shell about the body and extending substantially between the first and second surfaces thereof, a hood about the first surface for enveloping an individual""s head and having an opening for receiving an individual""s head and neck and first and second one-way valves carried by the mouthpiece, the first valve enabling flow of filtered air from the filter air outlet into the mouthpiece and preventing backflow of exhaled air into the filter, the second valve enabling air exhaled into the mouthpiece for flow into the hood and preventing backflow of air from the hood through the second valve to the mouthpiece.
In a further preferred embodiment according to the present invention, there is provided a personal emergency breathing system comprising a mask including a shaped body formed of an elastic non-porous material having along a first surface thereof a perimetrical seal for sealing about an individual""s nose and mouth, a mouthpiece carried by the body and projecting from the first surface thereof terminating in a bite block for gripping by the individual""s teeth, the bite block being shaped to draw the mask toward the individual""s face to maintain the seal about the individual""s nose and mouth upon the individual biting down on the bite block, the body having a chamber with an opening through one of the first surface and a second surface opposite the one surface and in communication with the mouthpiece, an air filter disposed in the chamber for filtering ambient air and having an air inlet for receiving ambient air and an air outlet for passing filtered air into the mouthpiece, the mask including a substantially rigid shell about the body and extending substantially between the first and second surfaces thereof, a hood carried by the mask about the first surface for enveloping an individual""s head and having an opening for receiving an individual""s head and neck and first and second one-way valves carried by the body, the first valve enabling flow of filtered air from the filter air outlet into the mouthpiece and preventing backflow of exhaled air into the filter, the second valve enabling air exhaled into the mouthpiece for flow into the hood and preventing backflow of air from the hood through the second valve to the mouthpiece.